What makes the index interesting is that it is not a fanciful construct but a real portfolio, a mini-mutual fund that will have its own ticket symbol, KBSPX. Agency executives are opening a brokerage account with another client, the Vanguard Group, into which will be deposited 300 shares of each of the 18 companies.

The 300 employees of Kirshenbaum Bond will be offered long-term cash and compensation incentives to mirror the performance of the stocks in the index, which they will be able to track each trading day on an intranet on the agency’s Web site.

MDC is spending an estimated $500,000 to start the index, which includes contributing four restricted shares of MDC stock to the fund for each Kirshenbaum Bond employee, for a total of 1,200 share.

The index is a version of efforts by a growing number of agencies to put skin in the game by showing clients they are willing to be paid based on how their work performs in the marketplace. Other examples include agencies taking ownership stakes in client companies or sharing revenue from the sales of products they advertise.